Method and apparatus for initializing optical recording media

ABSTRACT

A method and apparatus for initializing optical recording media is provided that detects the intensity of a reflective light off of an optical recording media and analyzes the initializing condition based on the detected intensity during an initializing process. The light is radiated on a rotating phase-change optical recording medium. The light may be moved in a radial direction of the optical recording medium. The detected intensity of the reflected light may be used to identify crystallized portions and amorphous portions of the optical media. The initialization process can be adaptively controlled to ensure proper initialization. If desired, re-initialization can be limited to those areas detected to be outside of the predetermined parameters.

This application is a divisional of application Ser. No. 10/078,423filed on Feb. 21, 2002 now U.S. Pat. No. 6,580,472 which in turn is adivisional of Ser. No. 09/199,472 filed Nov. 25, 1998 U.S. Pat. No.6,373,802 issued Apr. 16, 2002. The entire disclosure of applicationSer. No. 10/078,423 and U.S. Pat. No. 6,373,802 is expresslyincorporated by reference herein.

BACKGROUND OF THE INVENTION

A. Field of the Invention

The present invention relates to an apparatus and method forinitializing an optical recording media. The present invention alsorelates to an initializing apparatus for changing an amorphous recordinglayer of an optical disc into a crystal recording layer. The inventionmay be used to manufacture phase-change optical recording media. Thepresent invention also relates to a system for verifying uniformcrystallization of phase-change optical recording media.

B. Description of the Related Art

In optical recording discs with rewrite capability, such as a CD-RWphase-change optical recording disc, a first dielectric layer, arecording layer, a second dielectric layer and a metal layer are formedon a disc substrate. The substrate is generally made of polycarbonate. AUV hardening layer may be provided on the metal layer.

The phase-change recording material of the CD-RW optical disctransitions into either (1) a crystal condition by lengthening thecooling time after it has been heated, or (2) an amorphous condition byshortening the cooling time after it has been melted. Phase-changerecording media can record information in the form of marks byreversibly changing between the crystal condition and the amorphouscondition. A recording signal can be used to change the intensity of theoptical beam that is radiated on the recording layer to change therecording layer from a crystal condition to an amorphous condition, orvice versa. When forming marks, the optical beam intensity may be set atthe amorphous level. On non-mark portions, the intensity of the opticalbeam intensity is set at the crystal level, and the recording layer iscrystallized. Since non-mark portions are not heated as much and coolslowly, they transition into the crystal condition regardless of whetherthey were in an amorphous condition or in a crystal condition.

On the other hand, when manufacturing phase-change recording media, therecording layer is left in an amorphous condition after spattering.Therefore, it is necessary to crystallize all of the recording layer.This crystallization process is called the initialing process. Asmentioned above, the length of the cooling time effects the transitionto either the crystal condition or the amorphous condition. When thecooling time is longer, the recording layer transitions into the crystalcondition. When the cooling time is shorter, the recording layertransitions into the amorphous condition. Therefore, in the initializingprocess of the recording layer, an optical beam is radiated on therecording layer and the cooling time is made longer after raising thetemperature of the recording layer.

Because the substrate is generally made from polycarbonate, it ispossible to exceed the heat-resisting properties of the material if theentire surface is initialized simultaneously. The initializing processis generally carried out by radiating an optical beam on the opticalrecording media while rotating the optical recording media. Successiveportions of the recording layer are crystallized as the radiatingposition is moved in the radial direction.

One problem with the above-described scanning system is that anyinstability in the optical beam can result in incomplete crystalportions on the recording layer. If there are incomplete crystalportions, problems with recording and reproducing signals are caused,and it is impossible to record and reproduce information accurately.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aninitializing method and apparatus for determining if a recording layerof a phase-change optical recording disc is uniformly crystallized.

It is another object of the present invention to provide an initializingmethod and apparatus that can uniformly crystallize a recording layer ofa phase-change optical recording disc.

In one aspect of the invention, the intensity of light reflected off ofthe optical recording media is detected. Based on the intensity of thereflected light, a judgement is made as to whether the initializingcondition is acceptable or not. According to this aspect of theinvention, the light used for initializing may be radiated on a rotatingphase-change optical recording medium. The radiating position of thelight may be moved radially relative to the optical recording medium

In another aspect of the invention, the intensity of the reflectivelight of the optical recording media is detected and the driving powerof an initializing light source is adaptively adjusted. The initializinglight radiated by the light source may be based on the intensity of thereflective light.

In another aspect of the invention, the intensity of the reflectivelight off of the optical recording media is detected and the rotationspeed of the optical recording media and the relative moving speed ofthe initializing light in the radial direction of the optical recordingprocess is adjusted as a function of the intensity of the reflectivelight. The intensity detection and speed adjustment steps may occurduring the initialization process.

In another aspect of the invention, an initializing apparatus comprises:a driving means that drives an initializing light source for radiatingthe initializing light on optical recording media; a rotating means forrotating the optical recording media; a moving means for moving theradiating position from the initializing light source against theoptical recording media in a radial direction; a detecting means fordetecting the intensity of the reflective light of the optical recordingmedia in initializing action of the optical recording media; and ananalyzing means for determining if initializing conditions areacceptable or not based on the detected intensity of the reflectivelight.

In another embodiment of the invention, an initializing apparatuscomprises: a driving means which drives an initializing light source forradiating the initializing light on optical recording media; a rotatingmeans for rotating the optical recording media; a moving means formoving the radiating position from the initializing light source againstthe optical recording media in a radial direction; a detecting means fordetecting intensity of the reflective light of the optical recordingmedia in initializing action of the optical recording media; and anadjusting means for adjusting the driving power of the initializinglight source based on the detected intensity of the reflective light ofthe optical recording media.

In another embodiment, an initializing apparatus comprises: a drivingmeans which drives an initializing light source for radiating theinitializing light on optical recording media; a rotating means forrotating the optical recording media; a moving means for movingrelatively the radiating position from the initializing light sourceagainst the optical recording media in a radial direction; a detectingmeans for detecting the intensity of the reflective light of the opticalrecording media in initializing action of the optical recording media;and an adjusting means for adjusting a rotating speed of the opticalrecording media and the relative moving speed between the radiatingposition of the initializing light source and the optical recordingmedia based on the detected intensity of the light reflected by theoptical recording media.

In another aspect of the invention, the intensity of the reflectivelight is detected based on the reflection of the light radiated on theoptical recording media.

In another aspect of the invention, the intensity of the reflectivelight is detected based on the reflection of the light radiated on theoptical recording media by a second light source different from thelight source used for initializing.

In another aspect of the invention, the intensity of the reflected lightis determined and analyzed, the system responds accordingly, and theinitialization process is repeated.

In another aspect of the invention, a determination is made as towhether the optical recording medium was inadequately initialized. Thedetermination may be made during or after the initialization process.

In another aspect of the invention, the driving power of theinitializing light source is monitored and actively adjusted to preventpoor initializing conditions.

In another aspect of the invention, the rotation speed of the opticalrecording media and the relative moving speed of the initializing lightin the radial direction of the optical recording media are activelyadjusted to prevent poor initializing conditions.

In another aspect of the invention, optical focusing servo and trackingservo systems may be employed.

In another aspect of the invention, information on the reflective lightintensity is obtained by an exclusive optical arrangement independent ofthe reflective optical arrangement for the focusing servo and thetracking servo. This feature may be used to improve the reliability ofthe reflective light intensity information.

In another aspect of the invention, to carry out an initializingprocess, an initializing light source radiates an initialization lighton the rotating phase-change optical recording media, and the radiationposition is moved relatively in the radial direction of the opticalrecording media. The intensity of the reflective light of the opticalrecording media is detected. Based on the detected result, adetermination is made as to whether the initializing condition isacceptable or not. The intensity of the reflective light may be detectedduring or after the initializing process.

In another aspect of the invention, to carry out an initializingprocess, an initializing light from the initializing light source isradiated on the rotating phase-change optical recording media, and theradiation position is relatively moved in the radial direction of theoptical recording media. The intensity of the reflective light of theoptical recording media is detected, and the driving power of theinitializing light source is adaptively adjusted based on the detectedresult to prevent poor initializing conditions.

In another aspect of the invention, an initializing light from theinitializing light source is radiated on the rotating phase-changeoptical recording media, and the radiation position is relatively movedin the radial direction of the optical recording media. The intensity ofthe reflective light of the optical recording media is detected, and therotating speed of the optical recording media and the relative movingspeed of the initializing light in the radial direction of the opticalrecording media are adaptively adjusted based on the detected result toprevent poor initializing conditions.

With these and other objectives, advantages and features of theinvention that may become apparent, the nature of the invention may bemore clearly understood by reference to the following detaileddescription, the appended claims, and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a laminate structure of an optical recordingmedia constructed in accordance with the invention;

FIG. 2 is a diagram of an initializing apparatus;

FIG. 3 is a graph based on experimental results showing the error rateof an optical recording media after initializing by a conventionalmethod;

FIG. 4 is a graph based on experimental results showing the error rateof an optical recording media after re-initializing using changedparameters; and

FIG. 5 is a graph based on experimental results showing the error rateof an optical recording media initialized in accordance with the presentinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described in detailwith reference to the accompanying drawings.

FIG. 1 shows the laminate structure of a phase-change optical disc 1.The optical disc 1 is formed from a first protective layer 3, arecording layer 4, a second protective layer 5, a reflective layer 6, anovercoat layer 7, and a printing layer on the surface of the substrate2. A hard coat layer 9 is coated on the opposite surface of thesubstrate 2. The substrate 2 may be composed of polycarbonate or acrylicresin. The desired material may be selected based on opticalcharacteristics, forming characteristics and cost considerations. Thedesirable thickness is 1.2 mm or 0.6 mm.

The substrate 2 is not limited to a disc shape and may be a card form,sheet or other form. In addition, it is expressly contemplated thatother phase-change products may be used. The present invention is notlimited to the particular optical disc described herein but may be usedwith other phase-change optical recording media.

The first protective layer 3, the recording layer 4, the secondprotective layer 5 and the radiation reflective layer 6 can be formed asfilms by spattering techniques. These films may have thicknesses of65-130 nm, 15-35 nm, 15-45 nm and 7-180 nm, respectively. The recordinglayer 4 is composed of a phase-change recording material, andtransitions into a crystal condition when it is slowly cooled after itis melted, and transitions into an amorphous condition when cooledimmediately after heating. After spattering, the recording layer 4 is inan amorphous condition.

The over coat layer 7 has a 7-15 micro-meter (μm) thickness and isformed on the reflective layer 6. The printing layer 8 may be formedafter initializing the recording layer 4.

The recording layer 4 is heated by light radiated onto the substrate 2from the side of the hard coat layer 9. When the cooling time of therecording layer 4 is made longer after it has been heated, the recordinglayer 4 transitions into a crystal condition. When the cooling time ofthe recording layer 4 is made shorter after it has been heated, therecording layer 4 transitions into an amorphous condition.

FIG. 2 shows an initializing apparatus 10. The initializing apparatus 10may use a laser diode 11 as an optical resource for the initializationprocess. A rotating mechanism 12 is provided that includes a drivingresource and a moving mechanism 13. The laser diode may be substitutedwith another suitable source including, but not limited to, an electronbeam, X-rays, ultraviolet rays, visible rays, infrared rays, ormicrowaves.

A laser diode 11 is advantageous because it is compact and its power canbe controlled easily. The rotating mechanism 12 drives and rotates theoptical disc 1 based on commands from the control circuit 14 of themicrocomputer. The moving mechanism 13 makes the optical disc 1 move ina perpendicular direction against the rotating shaft based on commandsfrom the control circuit 14, and makes the focusing position of thelaser beam from the laser diode 11 move in a radial direction relativeto the disc 1.

The laser diode 11 may be driven by a laser diode power supplier 15,which is controlled by the control circuit 14. Laser rays from the laserdiode 11 are made parallel by the collimator lens 16, polarized by thepolarizing beam split means 17, and focused on the optical disc 1 by theobjective lens 18. Reflective rays from the optical disc 1 are deflectedat a right angle by the polarizing beam split means 17, deflected at aright angle again by a filter 19, pass through a quarter-wave plate 20,pass through a polarizing beam split means 21, and then are radiatedinto element 22 for controlling the focus servo signal. An actuator 23adjusts the objective lens 18 in the direction of the ray axis andadjusts the servo focus.

The initializing apparatus 10 has a beam split means 24 which deflectsthe polarized laser beam going straight to the polarizing beam splitmeans 21 at right angles. The laser beam polarized at right angles bythe beam split means 24 is received by a photo sensor 25. Anelectromotive force is generated in the photo sensor 25 in response tothe intensity of the received light. The electromotive force isconverted into a digital value and input to the control circuit 14. Thecontrol circuit 14 retains data on the optimum maximum value and minimumvalue of the electromotive force. The stored data may be based oncollected electromotive force data for the optical disc 1. Adetermination is made as to whether the disc 1 is a good one or notbased on whether the output signal value from the photo sensor 25 isbetween the maximum value and the minimum value.

Furthermore, the initializing apparatus 10 has a laser diode 26 for thefocus servo. The laser beam radiated from the laser diode 26 is changedinto a parallel beam by the collimator lens 27 and then goes to thepolarizing beam split means 21 before reaching the optical disc 1.

To initialize the recording layer 4, the optical disc 1 is rotated bythe rotating mechanism 12 and moved in a radial direction by the movingmechanism 13. The focus position of the laser beam radiated from thelaser diode 11 moves in a radial direction. The laser beam from thelaser diode 11 is radiated on the optical disc 1 and the recording layer4 is heated. The recording layer 4 transitions into the crystalcondition by slowly cooling after heating.

If the thickness and other properties of the recording layer 4 are notuniform, there are portions that may require a higher laser beam powerfor adequate heating and melting and portions that require a lower laserbeam power. Even if the cooling speed is equal, there may be crystalportions and amorphous portions. According to the present invention, inorder to achieve a uniform property in the optical disc 1, and toachieve the desired initialization, the reflective rate of the opticaldisc 1 is monitored during the initializing step and adjustments arecarried out. The well melted portions of the optical disc 1 will be wellcrystallized and the reflective rate will be high. On the other hand,the reflective rate of the optical disc 1 is saturated when exceeding acertain initializing power. When the cooling speed is fast, therecording layer 4 becomes amorphous and the reflective rate is sharplyreduced. It is thus possible to monitor the initialization process bycorrelating reflective rate with crystallized/amorphous portions. In thepresent embodiment, the control circuit 14 monitors the output from thephoto sensor 25 to determine if it is between the predetermined maximumvalue and the predetermined minimum value, and determines if theinitializing condition of the optical disc 1 is acceptable or not.

Instead of varying the laser beam intensity, or in addition to,adjustments to the driving power of the laser diode 11 by the laserdiode power supplier 15, and/or to the driving speed of the rotatingmechanism 12, and/or to the moving mechanism 13 can be carried out bycontrol of the control circuit 14. Thus, when the reflective rate isdetermined to be low, the control circuit 14 returns the results to thelaser diode power supplier 15 to make the reflective rate higher. On theother hand, when the reflective rate is too high, the laser diodedriving power supplier 15 can act to reduce the laser power. It is thuspossible to raise or lower the reflective rate and ensure adequateinitialization.

The whole surface of the optical disc 1 can be scanned to determine ifthe output of the photo sensor 25 exceeds the minimum value. Forexample, if there is a sharp decline in the reflective rate or if theaverage reflective rate of the optical disc 1 is under 70%, which showsthe optical disc 1 is in a partially amorphous condition, the rotatingmechanism 12 and the moving mechanism 13 can be adjusted accordingly.The rotating speed and the moving speed of the optical disc 1 can beadaptively slowed to prevent the recording layer 4 from transitioning toan amorphous condition.

If the control circuit 14 recognizes that there is an amorphous portionon the optical disc and/or the reflective rate is too high and/or toolow based on the result of the monitoring after initializing once, theinitializing process for the whole optical disc 1 can be repeated. Thedriving power of the laser diode 11 by the laser diode power supplier 15and/or the rotating speed and/or the moving speed of the optical disc 1by the rotating mechanism 12 and/or the moving mechanism 13 can beadjusted accordingly. Therefore, non-uniformity of the reflective rateis reduced and the generated amorphous portions are crystallized.

Alternately, since re-initialization is time consuming, the results ofthe initialization monitoring can be used to calculate the radial valueof the optical disc 1 corresponding to amorphous, or potentiallyamorphous, regions. Parameters may be automatically determined toinitialize only portions requiring re-initializing.

The photo sensor 25 of the present invention monitors a reflective lightfrom the optical disc 1 for focusing servo. However, an exclusive lightsource for monitoring the initializing process also can be provided.

The efficiency of the present invention was determined experimentally.The results of the experiments are shown in FIGS. 3, 4 and 5.

A first protective layer, a recording layer, a second protective layerand a reflective layer were continuously formed on a polycarbonatesubstrate of 1.2 mm thickness with grooves of 0.5 μm width and a depthof 35 nm by a spattering apparatus. In the next step, a hard coat layerand an over coat layer were formed using a spin coat method and aphase-change optical disc is made. The first protective layer and thesecond protective layer were composed of ZnS—SiO2. The reflective layerwas composed of aluminum alloy. After the recording layer wasinitialized, a printing layer was formed on the over coat layer.

The error rate of the phase-change optical disc was examined by avaluing machine with an optical pick-up device of 780 nm wave and NA0.5. Keeping the read power 1.0 mW, the error rate of every 20 trackswas examined in mode of 1200 rpm and CLV.

FIG. 3 shows a graph of the error rate when the disc was not coolingwell after initializing and amorphous portions were generated aroundATIP 70 min.

FIG. 4 shows the result of re-initializing the optical disc usingdifferent parameters. Amorphous portions generated around ATIP 70 minare restored perfectly.

FIG. 5 is a graph of the error rate of the initialized optical discwhile adjusting the initializing conditions during initializing. Thisdata indicates that this optical disc has low error rate on the wholesurface.

As mentioned above, optical recording media can be uniformly produced.It is unnecessary to add another process examining an optical recordingdisc with amorphous portions. It is unnecessary to postpone the processtime, and it is possible to remove errors.

In accordance with the present invention, initializing power can beadjusted in response to the reflective rate of the optical disc detectedin the initializing process. Therefore, it is possible to manufactureand initialize optical recording media with a uniform reflective rate.It is possible to reduce error generation of recording and reproducingin a recording and reproducing apparatus.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size and arrangement of parts and steps, or a combination of both withinthe principles of the invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

The entire disclosures of Japanese Patent Applications Nos. 09-325808and 10-60755, filed Nov. 27, 1997 and Mar. 12, 1998, respectively, areexpressly incorporated herein by reference.

What is claimed is:
 1. An optical recording medium comprising arecording layer and a substrate for supporting the recording layer, therecording layer being initialized by the following process: rotating theoptical recording medium; changing the recording layer from an amorphouscondition to a crystal condition by radiating an initializing light ontoa portion of the recording medium; moving the light in a radialdirection relative to the recording medium; detecting the intensity oflight reflected by the portion of the recording medium; analyzing theinitializing condition of the portion of the recording medium based onthe detected intensity of the reflected light; and adjusting therelative moving speed of the initializing light as a function of thedetected intensity of the reflected light.
 2. The optical recordingmedium of claim 1, wherein the initializing process further comprisesthe step of adjusting the driving power of an initializing light sourceas a function of the intensity of the detected reflected light.
 3. Theoptical recording medium of claim 1, wherein the reflected light is areflection of the initializing light.
 4. The optical recording medium ofclaim 1, wherein the initializing process further comprises the step ofrepeating an initializing action on the optical recording medium as afunction of the analyzed condition of the recording medium.
 5. Theoptical recording medium of claim 2, wherein the reflected light is areflection of the initializing light.
 6. The optical recording medium ofclaim 2, wherein the initializing process further comprises the step ofrepeating an initializing action on the optical recording medium as afunction of the analyzed condition of the recording medium.
 7. Anoptical phase-change recording medium formed by a method comprising thesteps of: rotating the optical recording medium; radiating aninitializing light onto the recording medium; moving the light in aradial direction relative to the recording medium; detecting theintensity of light reflected by the recording medium; analyzing thecondition of the recording medium based on the detected intensity of thereflected light; and adjusting the rotating speed of the opticalrecording medium and the relative moving speed of the initializing lightas a function of the detected intensity of the reflected light.
 8. Theoptical phase-change recording medium of claim 7, wherein the reflectedlight is a reflection of the initializing light.
 9. The opticalphase-change recording medium of claim 7, wherein the reflected light isa reflection of light from a second light source, and wherein the secondlight source is different than the first light source.
 10. The opticalphase-change recording medium of claim 7, wherein the method of formingthe recording medium further comprises the step of repeating aninitializing action on the optical recording medium as a function of theanalyzed initialization condition of the recording medium.
 11. Anoptical phase-change recording medium manufactured by a methodcomprising the steps of: rotating the optical recording medium;radiating an initializing light onto a portion of the recording medium;moving the light in a radial direction relative to the recording medium;detecting the intensity of light reflected by said portion of therecording medium; and analyzing the condition of the recording mediumbased on the detected intensity of the reflected light, wherein thereflected light is a reflection of light from a second light source, andwherein the light from the second light source is different than theinitializing light.
 12. An optical phase-change recording mediummanufactured by a method comprising the steps of: rotating the opticalrecording medium; radiating an initializing light onto a portion of therecording medium; moving the light in a radial direction relative to therecording medium; detecting the intensity of light reflected by theportion of the recording medium; analyzing the initializing condition ofthe portion of the recording medium based on the detected intensity ofthe reflected light; and adjusting the driving power of an initializinglight source and the rotating speed of the optical recording medium as afunction of the intensity of the detected reflected light, wherein thereflected light is a reflection of light from a second light source, andwherein the second light source is different than the initializing lightsource.
 13. A method of employing an initialized optical recordingmedium to reproduce data, the method comprising the steps of: providinga recording layer and a substrate for supporting the recording layer,the recording layer being initialized by the process of rotating therecording layer; changing the recording layer from an amorphouscondition to a crystal condition by radiating an initializing light ontoa portion of the recording medium; moving the light in a radialdirection relative to the recording medium; detecting the intensity oflight reflected by the portion of the recording medium; analyzing theinitializing condition of the portion of the recording medium based onthe detected intensity of the reflected light; and adjusting therelative moving speed of the initializing light as a function of thedetected intensity of the reflected light; and adjusting the relativemoving speed of the initializing light as a function of the detectedintensity of the reflected light; and reproducing data from theinitialized optical recording medium.
 14. The method of claim 13,wherein the initialization process further comprises the step ofadjusting the driving power of an initializing light source as afunction of the intensity of the detected reflected light.
 15. Themethod of claim 13, wherein the reflected light is a reflection of theinitializing light.
 16. The method of claim 13, wherein theinitialization process further comprises the step of repeating aninitializing action on the optical recording medium as a function of theanalyzed condition of the recording medium.
 17. The method of claim 14,wherein the reflected light is a reflection of the initializing light.18. The method of claim 14, wherein the initialization process furthercomprises the step of repeating an initializing action on the opticalrecording medium as a function of the analyzed condition of therecording medium.
 19. A method of employing an initialized opticalphase-change recording medium to reproduce data, comprising the stepsof: providing an initialized optical phase-change recording medium, theinitialized optical recording medium being manufactured by a processthat includes the steps of: rotating the optical recording medium;radiating an initializing light onto the recording medium; moving thelight in a radial direction relative to the recording medium; detectingthe intensity of light reflected by the recording medium; analyzing thecondition of the recording medium based on the detected intensity of thereflected light; and adjusting the rotating speed of the opticalrecording medium and the relative moving speed of the initializing lightas a function of the intensity of the detected reflected light; andreproducing data from the initialized optical phase-change recordingmedium.
 20. The method of claim 19, wherein the reflected light is areflection of the initializing light.
 21. The method of claim 19,wherein the reflected light is a reflection of light from a second lightsource, and wherein the second light source is different than theinitializing light.
 22. The method of claim 19, further comprising thestep of repeating an initializing action on the optical recording mediumas a function of the analyzed condition of the recording medium.
 23. Amethod of using an initialized optical phase-change recording medium toreproduce data, comprising the steps of: providing an initializedoptical phase-change recording medium, the initialized optical recordingmedium being formed by a method comprising the steps of: rotating theoptical recording medium; radiating an initializing light onto therecording medium; moving the light in a radial direction relative to therecording medium; detecting the intensity of light reflected by therecording medium; and analyzing the condition of the recording mediumbased on the detected intensity of the reflected light; and wherein thereflected light is a reflection of light from a second light source, andwherein the light from the second light source is different than theinitializing light; and reproducing data from the initialized opticalphase-change recording medium.
 24. A method of using an initializedoptical phase-change recording medium to reproduce data, comprising thesteps of: providing an initialized optical phase-change recordingmedium, the initialized optical recording medium being formed by amethod comprising the steps of: rotating an optical recording medium;radiating an initializing light onto a portion of the recording medium;moving the light in a radial direction relative to the recording medium;detecting the intensity of light reflected by the portion of therecording medium; analyzing the initializing condition of the portion ofthe recording medium based on the detected intensity of the reflectedlight; and adjusting the driving power of an initializing light sourceand the rotating speed of the optical recording medium as a function ofthe intensity of the detected reflected light, wherein the reflectedlight is a reflection of light from a second light source, and whereinthe second light source is different than the initializing light source;and reproducing data from the initialized optical phase-change recordingmedium.
 25. An initializing apparatus for changing an amorphousrecording layer of an optical recording medium into a crystal recordinglayer, said apparatus comprising: a driver for driving an initializinglight source for radiating an initializing light onto a portion of theamorphous recording layer of the optical recording medium to change theamorphous recording layer into the crystal recording layer; a device forrotating the optical recording medium; a device for moving theinitializing light in a radial direction relative to the opticalrecording medium; a detector for detecting the intensity of lightreflected by the portion of the optical recording medium; an evaluatorfor evaluating the initializing condition of the portion of therecording medium based on the detected intensity of the reflected light;and a circuit for adjusting the rotating speed of the optical recordingmedium as a function of the intensity of the detected reflected light.26. The initializing apparatus of claim 25, wherein the intensity of thereflected light is detected based on the reflection of the initializinglight.
 27. The initializing apparatus of claim 25, further comprising are-initialization device for repeating an initializing action on theoptical recording medium as a function of the initialization conditionof the recording medium.
 28. An initializing apparatus, comprising: adriver for driving an initializing light source for radiating aninitializing light onto an optical recording medium; a device forrotating the optical recording medium; a device for moving theinitializing light in a radial direction relative to the opticalrecording medium; and a detector for detecting the intensity of lightreflected by the optical recording medium, wherein the apparatus adjuststhe rotating speed of the optical recording medium and the relativemoving speed of the initializing light in the radial direction as afunction of the detected intensity of the reflected light.
 29. Theinitializing apparatus of claim 28, wherein the intensity of thereflected light is detected based on the reflection of the initializinglight.
 30. The initializing apparatus of claim 28, wherein the reflectedlight is a reflection of light from a second light source, and whereinthe second light source is different than the initializing light source.31. The initializing apparatus of claim 28, further comprising are-initialization device for repeating an initializing action on theoptical recording medium as a function of the initialization conditionof the recording medium.
 32. An initializing apparatus, comprising: adriver for driving an initializing light source for radiating aninitializing light onto a portion of an optical recording medium; adevice for rotating the optical recording medium; a device for movingthe initializing light in a radial direction relative to the opticalrecording medium; a detector for detecting the intensity of lightreflected by the portion of the optical recording medium; an evaluatorfor evaluating the initializing condition of said portion of therecording medium based on the detected intensity of the reflected light,wherein the reflected light is a reflection of light from a second lightsource, and wherein the second light source is different than theinitializing light source; and a circuit for adjusting the relativemoving speed of the initializing light in the radial direction as afunction of the detected intensity of the reflected light.